#include<stdio.h>
#include<math.h>
double x1,x2,x3,yy1,y2,y3;
double cc,jjud;
double disp2p(double q1 ,double r1 ,double q2,double r2 );
int main(){
	scanf("%lf%lf%lf%lf%lf%lf",&x1,&yy1,&x2,&y2,&x3,&y3);    
	//cin >>x1 >>y1>>x2>>y2>>x3>>y3;
	cc +=disp2p(x1,yy1,x2,y2);
	cc +=disp2p(x1,yy1,x3,y3);
	cc +=disp2p(x3,y3,x2,y2);
	printf("%.2f",cc);
	return 0;
}
double disp2p(double q1 ,double r1 ,double q2,double r2 ){
	double temp  = sqrt(((q1-q2)*(q1-q2))+((r1-r2)*(r1-r2)));
	if (!temp ) return 0;
	return temp;
}
